Method of manufacturing nickel-plated steel plate



3,245,885 Pntented Apr. 12, 1966 METHOD OF MANUFACTURING NICKEL-PLATED STEEL PLATE I Hidejiro Asano and Kiyoshi Segawa, Kitakyushu, Japan, assignors to Yawata Iron & Steel Co., Ltd., Tokyo, Japan, a corporation of Japan No Drawing. Filed Oct. 5, 1964, Ser. No. 401,686 8 Claims. (Cl. 204-35) This application is a continuation-in-part of our pend ing application Serial No. 176,113 filed on February 21,

This invention relates to a method of producing a nickel-plated steel plate in which the plating is very thin and which is especially high'in anticorrosiveness, solderability, lacquerability and workability. I

' Heretofore, the plated articles have been mostly used for food cans and miscellaneous other cans. Tin

plates have excellent, properties in various points. Steel plateselectroplated with any other metal than tin have i In -thej'treating method according to the present inventron, the cathode-treatment of the plated product is suflicient but, if the anode-treatment of the plated product is additionally carried out following the above mentioned cathode-treatment depending on the plated state, more favorableresults may be obtained.

However, the anode-treatment is to be carried out for a treating time of less than 1 second at a current density v QfQLAQ/dfn. in the above mentioned treating solution.

never been used folflrnaterials for making cam, because there has been found nothing superior to tin in respect of anticorrosiveness, solderability, lacquerability, poisonlessness and workability. For example, in nickel-plating and the like, in order to obtain suflicient anticorrosiveness, it is necessary to make the plating more than several microns thick and it is usual to make it more than, 10 microns thick. Such'thick' nickel-plating is not only disadvantageous ineconomy but is also low in workability. From the view point of workability and economy, the thinner the plating, the more preferable it is. However, if the plating is toothin, its anticorrosiveness will be lower. I 1

An object of the present invention is to provide a method of producing a plated steel plate in which the plate is very thin and which is advantageous in economy and high in workability.

Another object of the present invention is to provide a method of producing a very thinly plated steel plate which is high in not only anticorrosiveness but also heatproofness, solderability, poisonlessness and lacquerability.

For the above mentioned objects, according to the present invention, a steel plate is first very thinly plated with nickel or nickel alloyand then the thus platedsteel sheet is furthersubjected to a'surface treatment for coat-' ing its whole surface with a pasivated film, including not only the nickel or nickel alloy surface, but also such points which are low in anticorrosiveness as pinholes.

A'nickel-plating of steel sheet may be carried out, for instance, with nickel or such alloy as of Ni-Fe or Ni-Sn about 0.04 to 0.3 micron thick according to conventional methods. Then, 'the nickel plated sheet is subjected to an electrochemical treatment as characterized by the present invention.

The surface treatment specified by the present invention shall be detailed in the-following. The treating solution to be used in the surface treatment is an aqueous solution of 1 to 5% sodium salt or potassium salt of dichrornic acid or 'chromic' acid as alone or mixed, or chromic anhydride. It is effective and economical to keep its concentration within a range of 1 to 5%. That is to say, when the concentration is less than 1%, the solution will be so dilute that it will be diflicult to obtain the expected eifect. When the concentration is more than 5%, the solution will be uneconomical. The optimum time for the cathode-treatment of'the material to be treated in the treating solution is 1 to 10 seconds at a current density of 15 to 4.0 A./dm.= from the viewpoint of the effect and industrial economy. Above the upper limit of this range, the treatment will be, uneconomical. Below the lower limit, the effect will be very low.

values, there will be rather an unfavorable influence on the platedflayer. The anticorrosiveness and lacquerability of the thus obtained very thinly nickel-plated or nickel alloy-plated steel plate is as high or higher than that of a. tin plate. The solderability thereof is not lower than of the plate. The plating according to the present inventionis so thin that the workability is high and the cost is Even when it is exposed to air at 600 C. for about .hOUlS, itwill retain sufficient heatproofness. The layer of such plate is thought to consist of a dense oxidated film and is well passivated.

,The comparison of the anticorrosiveness of the thus nickel-plated steel plate with that of a tin plate is as in following table. For information, in the table are also given those of a steel plate and a steel plate plate with Ni 0.06 micron thick but not passivated.

\ RESULTS OF SALT WATER SPRAY TESTS [Test/ad for 3 hours. Numerals in the table represent rusted areas in 7 percent] Tin plate 0.06 micron nickelplated steel plate Steel Samples plow Product of the present invention Not surfacetreated Rustedareasinpercent"- so -10o s s 0.5 1-10 Not only Ni but also Cr and Sn are considered to be poisonless plating metals for food cans and, the like. However, lustrous plating of Sn is dilficult.v In order tojproduce luster, it is necessary to melt the plating after it is made; A thickness of at least about 0.5 micron is required therefor. Thus, a very thin plating is diflicult.

I On the other hand, when a steel plate plated with Cr or a Cr Fe alloy about 0.04 to 0.3 micron thick, and thereupon electrochemically treated on the surface was subjected to a salt water spray test, an entirely contrary eflfect was obtained, showing a reduced anticorrosiveness'.

Surface treating solution:

Aqueous solution of 2.0% sodium dichromate. Surface treating conditions:

Cathode-treatment at 2.5 A./dm. for 3 seconds.

The opposed electrodes were made of very mild steel plate. By the above-mentioned method there have been produced nickel-platings of various thickness which were immediately subjected to the above mentioned surface treatment.

In testing the properties of various samples of the plated steel sheets prepared by the above mentioned method the following results have been achieved.

In the salt water spray test for 3 hours, only 0.5% of the area was averagely rusted and the anticorrosiveness of the products was proved to be higher than of a tin plate.

The Erichsen value and tensile strength of the" samples were exactly the same as of the original plate. The mechanical properties were never impaired by plating. In this respect, the thus nickel-plated steel plates were superior to the tin plate.

The expansion and adhesiveness of a lacquer on the samples were investigated. Though it was diflicult to quantitatively indicate them, the lacquerability of the products was evidently higher than of the tin plate.

The results of the soldering tests by the normal method with a solder of SnzPb=30z70 were as in the following table. An aqueous solution of 10% zinc chloride was used for the flux.

4 Surface treating solution:

Aqueous solution-of 2 to 4% mixed solution of potassium dichromate and potassium chromate. Temperature of bath, C. 40 to 50 Surface treating conditions:

Cathode treatment at 3 A./dm. for 3 toS seconds.

treatment at 0.1 A./ dm. for 1 second. v The tests of the products prepared according to the methods in Examples 2, 3, 4 and 5 showed the substantially sameresults-as in E itample 1 I i v w (6) Ni-Sn alloy plating Composition of the plating bath: a 6/1. Tin chloride 40 Nickel chloride 300 Acidic ammonium fluoride 55 The bath was adjusted to. be of a pH of 2.5 with ammonia water.

treatment.

Sample No.1 No. 2 No.3 No. 4 No.5 No.6 No.7 No.8 No. 0

Thickness orm nnngm 0. 01 0. 02 0.04 0.06 0.08 v 0.10 0.20 0.30 0.35 .Solder rise 111mm 14.0 20.5 18.0 21.0. 21.2 200 21.0 21.0 21.5 AdhesivenessinkgJin 7.0 9.0 11.0 15.5 18.0 20.0 223 24.2 24.6

Valuessubstantially the same as in the case of the tin Plating conditionsz plate were obtained. Bath temperature 60 C.

According to the results of experiments, when the thick- Current density 3 A./drn. ness of the nickel plating was less than 0.02 micron, the Anode Alloy of Sn:Ni=6:4. anticorrosiveness was not suflilcient. When the thickness Time 10 seconds. was morethan 0.3 micron, not only the plating was dis- Thickness of plating 0.18 micron. advantageous ineconomy but also the workability was Surface treating conditions: v somewhat reduced. 4 The most preferable thickness was Cathode treatment at 3 AJd-m. for-3 seconds. about 0.06 to 0.15 micron. Anode treatment at 0.1 A./dm. for 1 second.

(2) Nickel-plating The product of the present invention made by the above The steel sheet nickel-plated according to the method m the followmg pmpcmes: of Example 1 was subjected to the f nc i u f Anttcorrosrveness: In the salt water spray test for3hours, treatment.. only 0.5 to 1.0% of the area was rusted. workability: Both Erichsen value and tensile strength 01 Surface treating sohmon: the product were not difierent from those of the original Aqueous solution of 2 to 3% potassium dichromate. plate. Temperature of bath a to Lacquer-ability: The high temperature baking on the prodsurface treating not was possible. The lacquerability of the product Cathode treatment at 3 A./dm. for 3 seconds. 45 was high. than of a tin mate" Anode manner at 7 AJdm-a for 1 o Solderability: When an aqueous solution of zinc chloride (3) Nickel-plating was used for the flux, the solderability of the produc1 The steel sheet ni'kel-plated accordingto the method was not were! from that of the m plate of Example 1 was subjected to the following surfac (7) Ni-Fe alloy plating treatment- Composition of the plating bath: Surface treating solution: G./l Aqueous solution of '2 to 4% chromic anhydride Nickel sulphate 13! sJ- I Iron sulphate I 1; Temperature of bath, C. 40 to Ammonium chloride 31 Surface treating conditions: Boric acid 3t Cathode treatment at 3 A./dm.'- for 3 seconds. I pH, 4 at; 5.

P ating co 'tions: Nickel plaung 60 Bath temperature 60 C. The steel sheet nickel-plated according to the method Current density 2 A./dm.. of Example 1 was subjected to the following surface Anode (A) Alloy of Fe:Ni=64:3t treatment. I Anode (B) Alloy of Fe:Ni=55:4 Surface treating solution: .20 seconds.

Aqueous solution of 2 to 4% mixed solution of 65 Thfckmss of P139113 (A) l sodium dichromate and sodium chromate. 9m. of Flam! (B) f mlcron- Temperature of bath, C. 40 to 50 Composmons of anodesand P g 111 Percent: Surface treating conditions:

Cathode treatment at 3 A./dm. for 3 to 5 seconds. mgigggg Anode treatment at 0.1 A./dm.' for lsecond.

(5) Nickel-plating Fe Ni Fe Ni The steel nickel-plated according to the method of A 64 36 8M 18 Example 1 was; subjected to the following surface 2 ss 45 20.1 at

Surface treating conditions:

Cathode treatment at 3 A./dm. for 3 seconds. Anode treatment at 0.1 A./dm. for 1 second.

Thus, the composition of the electrodeposit of the Fe-Ni alloy plating wasdifiicult to adjust. However, when the electrodeposit was surface-treated according to the present invention, a favorable anticorrosiveness was shown. That is to say, in the salt water spray test for 3 hours,

only and 0.5% of the area were rusted in (A) and (B), respectively.

Further, the workability-of the product was the same as of the original plate. The lacquerability of the product-was higher than of the original plate.

' As evidently seen from the above mentioned, the plated steel plate of the present invention consists of a layer of Ni or a layer composed mainly of Ni ranging 'from 0.02 to 0.3 micron thick on a steel plate and a passivated film of the surface of said layer. This structure seems to render the plated sheet the features of being high in anticorrosiveness, solderability, lacquerability, workability and heatproofness', that is, properties the same as or better than of a tin plate. On the other hand, as it may be much cheaper prepared than the latter, it is a very advantageous material for makingcans. I What is claimed is:

- 1. A method of producing -a very thinly nickel-plated steel sheet comprising the steps of plating a steel sheet with a substance selected from a group consisting of nickel and nickel base alloy about 0.04 to 0.3 micron thick, cathode-treating said nickel-plated steel sheet at a current density of 1.5 to'4.0 A./dm. for from 1 to 10 seconds in an aqueous solution of from 1 to 5% of a compound selected from a group consisting of sodium dichromate and potassium dichromate.

2. A method of producing a very thinly nickel-plated steel sheet comprising the steps of plating a steel sheet with a substance selected from a group consisting of nickel and nickel base alloy about 0.04 to 0.3 micron thick, cathode-treating said nickel-plated steel sheet at a current density of 1.5 to 4.0 A./dm. for from 1 to 10 seconds in an aqueous solution of from 1 to 5% of a mixture of sodium dichromate and sodium chromate.

3. A method of producing a very thinly nickel-plated steel sheet comprising the steps of plating a steel sheet with a substance selected from a group consisting of nickel and nickel base alloy about0. 04 to 0.3 micron thick, cathode-treating said nickel-plated steel sheet at a current density of from 1.5 to 4.0 A./dm. for from 1 to 10 seconds in an aqueous solution of from 1 to 5% of a mixture of potassium dichromate and potassium chromate.

4. A method of producing avery thinly nickel-plated steel sheet comprising the steps of plating'a steel sheet with a substance selected from a group consisting of nickel and nickel base alloy about 0.04 to 0.3 micron thick, cathode-treating said nickel-platedsteel sheet at a current density of from 1.5 to 4.0 A./dm. of from 1 to 10 seconds in an aqueous solution of from 1 to 5% of chromic anhydride. 1

5. A method claimed in claim 1, in which a nickelplated steel sheet is anode-treated at a current density of 0.1 A./dm. for 1 second after the cathode-treatment.

6. A method claimed in claim 2 in which a nickelplated steel sheet is anode-treated at a current density of 0.1 A./dm. for 1 second after the cathodetreatment.

7. A method claimed in claim 3in which a nickelplated steel sheet is anode-treated at a current density of 0.1 A./dm. for 1 second after the cathode-treatment.

8. A surface treating method for nickel alloy-plated steel plates characterized in that a steelplate plated with any of nickel and an alloy composed mostly of nickel is cathode-treated at a current density of 1.5 to 4.0 A./dm.

for 1 to 10 seconds in an aqueous solution of l to 5% of any of sodium salt and potassium salt of any of dichromic acid and chromic acid as alone and mixed.

References Cited by the Examiner UNITED STATES PATENTS 1,513,120 10/1924 Madden 204--56 X 1,998,496 4/ 1935 Fiedler. 3,090,733 5/1963 Brown 29-1966 WINSTON A. DOUGLAS, Primary Examiner.

W. VAN SISE, Assistant Examiner. 

1. A METHOD OF PRODUCING A VERY THINLY NICKEL-PLATED STEEL SHEET COMPRISING THE STEPS OF PLATING A STEEL SHEET WITH A SUBSTANCE SELECTED FROM A GROUP CONSISTING OF NICKEL AND NICKEL BASE ALLOY ABOUT 0.04 TO 0.3 MICRON THICK, CATHOD-TREATING SAID NICKEL-PLATED STEEL SHEET AT A CURRENT DENSITY OF 1.5 TO 4.0 A./DM.2 FOR FROM 1 TO 10 SECONDS IN AN AQUEOUS SOLUTION OF FROM 1 TO 5% OF A COMPOUND SELECTED FROM A GROUP CONSISTING OF SODIUM DICHROMATE AND POTASSIUM DICHROMATE. 